The present invention is related to Japanese patent application No. 2000-10155, filed Jan. 14, 2000; the contents of which are incorporated herein by reference.
The present invention relates to an air passage switching device, and more particularly to an air passage switching device for switching air passages with a film-type sliding door.
In Japanese Unexamined Patent Publication No. H.8-258538, the present inventors have previously proposed an air passage switching device for switching air passages with a film-type sliding door. Based on this related art, the present inventors are developing the air passage switching device shown in FIG. 16. In this device under development, a substantially flat plate-shaped sliding door 27 is disposed slidably in the direction of arrow B in a case 12a, facing an opening face of an air passage 22 (23). This sliding door 27 includes a door plate 28 in which is formed an opening 28a and a film member 29 fixed to opposite ends of this door plate 28.
Here, slot-shaped anchoring holes (not shown) are provided in anchor tabs 29b at opposite ends of the film member 29. By fitting these slot-shaped anchoring holes over anchor pins 28c, provided integrally with side faces of the door plate 28, the ends of the film member 29 are anchored to the side faces of the door plate 28 so they can displace in the vertical direction of FIG. 16 within the range of the slot length dimension of the anchoring holes.
Then, when from the arrow A direction an air current blows against the inner face of the film member 29 through the opening 28a, a draft pressure causes the film member 29 to press against edge seal faces 22a (23a) of the air passage 22 (23) and seal the air passage 22 (23). And by the sliding door 27 sliding in the direction of arrow B along an inside face of the case 12a, the film member 29 opens and closes the air passage 22 (23) and thus switches the air passage. Also, an elastic member 30 made of a spongelike porous resin foam material or the like is disposed between the door plate 28 and the film member 29.
In this device under development, a disagreeable extraneous noise (a flapping noise) arises when the film member 29 is employed. And when the present inventors investigated the causes of this extraneous noise through experiment, it was found that the extraneous noise arises for the following reasons. Specifically, when either of the anchor tabs 29b at the ends of the film member 29 is positioned in an air current, the air current strongly strikes both the inner face and the outer face of this anchor tab 29b. Furthermore, because the flow passage between the inner side of the anchor tab 29b and the side face 28e of the door plate 28 is small and irregular in sectional shape, when air flows here, it promotes fluctuations in pressure difference across the inner and outer faces of the film member 29.
These fluctuations in pressure difference across the inner and outer faces of the film member 29 and reactions of the film member. 29 itself cause the film member 29 to undergo self-excited vibration. That is, because the anchor tabs 29b at the ends of the film member 29 are allowed by the slot-shaped anchoring holes to displace with respect to the side faces 28e of the door plate 28, the above-mentioned pressure difference fluctuations and film reactions cause the anchor tabs 29b at the ends of the film member 29 to repeat small displacements and undergo self-excited vibration. And as a result, the anchor tabs 29b at the ends of the film member 29 repeatedly interfere with the side faces 28e of the door plate 28 and produce extraneous noise.
It is therefore an object of the present invention to suppress the production of extraneous noise caused by self-excited vibration of anchor tabs at the ends of a film member in an air passage switching device using a film-type sliding door.
To achieve this and other objects, in a first aspect, the present invention provides an air passage switching device wherein anchor tabs at either end of a film member are anchored to side faces of a door plate. The door plate is provided with draft deflectors that prevent the inflow of air to between the anchor tabs and the side faces.
Accordingly, the inflow of air to between the anchor tabs of the film member and the side faces of the door plate is prevented by the draft deflectors of the door plate. Consequently, fluctuations in pressure difference between inside and outside the anchor tabs at the ends of the film member are suppressed and the production of extraneous noise caused by self-excited vibration of the anchor tabs at the ends of the film member is suppressed.
According to a second aspect, the draft deflectors are formed as flat plates positioned on upstream sides of the anchor tab ends.
In a third aspect, the draft deflectors are positioned on the upstream sides of the ends of the anchor tabs and are formed as gutters for receiving the ends of the anchor tabs. Here, both the inner and outer sides of the anchor tabs of the film member are covered by the gutter-shaped draft deflectors, and a main current of an air flow is prevented from directly striking the inner and outer sides of the anchor tabs. Consequently, the effect of suppressing self-excited vibration of the anchor tabs of the door plate is further increased.
In another aspect, the anchor tabs are anchored to the side faces of the door plate at a plurality of locations in the width direction of the film member. Also, an anchor span which is the spacing between the anchored parts of the anchor tabs at said plurality of locations is not more than 100 mm.
Experimental studies carried out by the present inventors have confirmed that making the anchor span 100 mm or less raises the constraining effect on the anchor tabs of the film member and increases suppression of the self-excited vibration of the anchor tabs.
In a fifth aspect, the sliding door comprises a flexible film member that presses against edge seal faces of the air passages. The member closes the air passages and a door plate having openings for allowing a draft pressure to act on the film member. The film member is provided at both ends, in a direction orthogonal to the sliding direction of the sliding door, with anchor tabs. These anchor tabs are anchored to side faces of the door plate. The case has concavities formed in inner walls for receiving the anchor tabs. The inflow of air to between the anchor tabs and the side faces is prevented by these concavities.
In this case, the inflow of air to between the anchor tabs and the side faces of the door plate is prevented by the concavities on the case side and the self-excited vibration of the anchor tabs is suppressed.
In a sixth provision, the door plate is provided on the side faces with guide pins slidably supported by the case and the anchor tabs are anchored to the side faces by means of these guide pins and are sandwiched between the side faces and inner wall faces of the case.
In this way, the guide pins can act as parts for the film member for anchoring, and the construction of the device is thus simplified. Furthermore, by the anchor tabs being sandwiched between the side faces and the inner walls of the case, the anchor tabs are prevented from slipping off the guide pins. As a result, the guide pins can be simple cylindrical pins, and there is no need for enlarged retaining portions to be formed at the tips of the guide pins this eases assembly of film member to the side faces of the door plate.
In another aspect, anchor tabs at opposite ends of the film member are bent toward side faces of the door plate. Grooves into which the ends of the anchor tabs can be inserted are provided in the side faces of the door plate. As a result of the ends of the anchor tabs being inserted into the grooves, the inflow of air to between the anchor tabs and the side faces is prevented by the bent shape of the anchor tabs. In this case, the self-excited vibration of the anchor tabs is suppressed by an extremely simple construction using a bent shape of the anchor tabs.
In an eighth provision, anchor tabs at opposite ends of the film member are anchored to side faces of the door plate at a plurality of locations in the width direction of the film member. Cutaways are formed in the anchor tabs between the locations at which the anchor tabs are anchored to the side faces.
In this case, because air can pass freely through the cutaways in the anchor tabs, fluctuations in pressure difference between inside and outside the anchor tabs are suppressed and consequently self-excited vibration of the anchor tabs is suppressed.
In another aspect, the film member comprises a seal face for pressing on edge seal faces of the air passages and anchor tabs bent from opposite ends of the seal face toward side faces of the door plate and anchored to the side faces. The bend angle of the anchor tabs with respect to the seal face is smaller than 90xc2x0.
In this case, because the anchor tabs have an acute bend angle, the ends of the anchor tabs come nearer to the side faces of the door plate and the gaps between the anchor tabs and the side faces of the door plate are narrowed. Consequently, it is less easy for air to flow into these gaps. As a result, self-excited vibration of the anchor tabs is suppressed.
In another aspect, the bend angle xcex8 is preferably in the range 80xc2x0 to 89xc2x0. When the bend angle xcex8 is made small, the ends of the anchor tabs directly contact the side faces of the door plate and cause a change in the shape of the seal face of the film member. This degrades sealing. Therefore, the bend angle xcex8 is given a lower limit of 80xc2x0. And the upper limit on the bend angle xcex8 is 89xc2x0, to obtain an acute bend shape angle.
In another aspect, the invention provides a vehicle air-conditioner wherein the sliding door opens and closes air passages through which air flows into a passenger compartment.